Environmental Forensic Investigation of PFAS Air Emissions, Atmospheric Deposition, and Groundwater Transport
Air Dispersion Modeling, Source Attribution, Environmental Fate and Transport, and Human Health Exposure Assessment
Project Overview
Per- and polyfluoroalkyl substances (PFAS) have become one of the most significant classes of emerging environmental contaminants because of their exceptional chemical stability, environmental persistence, and ability to migrate through multiple environmental media. Unlike many conventional contaminants that degrade over time, PFAS can remain in the environment for decades, allowing atmospheric releases to contribute to long-term accumulation in soil, surface water, groundwater, and ultimately drinking water supplies. As scientific understanding of PFAS has evolved, increasing attention has been directed toward atmospheric emissions as an important transport mechanism capable of distributing these persistent compounds far beyond their original source. Evaluating these complex environmental processes requires the integration of environmental chemistry, atmospheric science, hydrogeology, engineering, toxicology, exposure assessment, and environmental forensic science (U.S. Environmental Protection Agency [EPA], 2024; Interstate Technology & Regulatory Council [ITRC], 2024).
RoseyFields conducted a comprehensive environmental forensic investigation to evaluate the potential for airborne PFAS emissions generated during industrial thermal treatment operations to contribute to environmental contamination through atmospheric transport, surface deposition, and subsequent migration into groundwater resources. The investigation focused on reconstructing historical emission pathways, evaluating contaminant fate and transport, assessing long-term environmental persistence, and determining whether available scientific evidence supported a complete source-to-receptor exposure pathway. Rather than relying upon a single line of evidence, the investigation integrated engineering analyses, publicly available emissions information, environmental monitoring data, atmospheric dispersion modeling, hydrogeologic evaluation, and peer-reviewed scientific literature to develop a scientifically supported assessment of PFAS migration within the surrounding environment (Brusseau, 2018; Cousins et al., 2020).
The investigation incorporated review of facility operational information, regulatory records, emissions inventories, environmental monitoring data, engineering documentation, and current scientific literature describing PFAS atmospheric transport and environmental behavior. Advanced air dispersion modeling was performed using accepted regulatory methodologies to estimate atmospheric transport and deposition of PFAS under representative operating and meteorological conditions. The resulting deposition estimates were evaluated within the context of established hydrogeologic principles governing contaminant infiltration, vadose zone transport, groundwater recharge, and long-term environmental accumulation. By integrating atmospheric modeling with environmental chemistry and contaminant fate and transport analyses, the investigation developed a scientifically defensible evaluation of how airborne PFAS emissions may contribute to regional environmental contamination over extended periods of operation (U.S. Environmental Protection Agency [EPA], 2024; Sha et al., 2025).
This multidisciplinary investigation demonstrates the expanding role of environmental forensic science in evaluating emerging contaminants whose environmental behavior extends well beyond traditional groundwater investigations. Through the integration of air dispersion modeling, environmental chemistry, hydrogeology, toxicology, regulatory analysis, and exposure science, RoseyFields reconstructed potential contaminant migration pathways and evaluated the complete source-to-receptor relationship using a weight-of-evidence approach. Such comprehensive environmental forensic investigations provide scientifically rigorous evaluations that support environmental consulting, regulatory investigations, environmental due diligence, and complex environmental litigation involving persistent contaminants capable of affecting multiple environmental media (National Academies of Sciences, Engineering, and Medicine, 2022; U.S. Environmental Protection Agency [EPA], 2024).
Chemicals of Concern
The primary chemicals of concern evaluated during this environmental forensic investigation were per- and polyfluoroalkyl substances (PFAS), a diverse class of synthetic fluorinated compounds widely recognized for their exceptional chemical stability, resistance to degradation, and environmental persistence. Because of the strength of the carbon-fluorine bond, PFAS are resistant to thermal, chemical, and biological degradation, allowing them to persist in air, soil, surface water, groundwater, sediments, and biota for decades after release. Their persistence, combined with increasing evidence of adverse human health effects, has resulted in heightened regulatory attention and growing interest in understanding the environmental transport pathways associated with industrial emissions (U.S. Environmental Protection Agency [EPA], 2024; Interstate Technology & Regulatory Council [ITRC], 2024).
Particular emphasis was placed on perfluorooctanoic acid (PFOA), one of the most extensively studied PFAS compounds due to its widespread historical use, environmental persistence, and occurrence in drinking water supplies worldwide. PFOA has been associated with a variety of industrial applications and may be released during manufacturing, thermal treatment, waste management activities, or the degradation of precursor compounds. Numerous epidemiological and toxicological investigations have associated long-term PFOA exposure with adverse health outcomes, including developmental effects, immune system impacts, altered liver function, increased cholesterol levels, kidney disease, and certain cancers. These findings have prompted increasingly stringent drinking water standards and regulatory guidance throughout the United States and internationally (National Academies of Sciences, Engineering, and Medicine, 2022; U.S. EPA, 2024).
The investigation also considered the behavior of PFAS precursor compounds that may undergo environmental or thermal transformation into terminal degradation products such as PFOA. The environmental significance of these precursor compounds extends beyond their direct toxicity because they can contribute to long-term PFAS loading through transformation processes occurring during industrial operations or after environmental release. Consequently, environmental forensic investigations must evaluate both direct emissions of persistent PFAS compounds and the potential contribution of precursor compounds capable of generating environmentally stable end products over time (Cousins et al., 2020; U.S. EPA, 2024).
Unlike many conventional air pollutants that degrade relatively quickly following atmospheric release, PFAS associated with fine airborne particles or aerosols may remain suspended long enough to undergo regional atmospheric transport before depositing onto terrestrial or aquatic environments. Recent research has demonstrated that atmospheric emissions can represent an important mechanism for distributing PFAS over considerable distances, particularly when contaminants are associated with respirable particles capable of remaining airborne for extended periods. Following atmospheric deposition, PFAS may infiltrate soils, migrate through the vadose zone, enter groundwater systems, or be transported into surface water bodies, thereby creating complete environmental exposure pathways that extend well beyond the original emission source (Sha et al., 2025; Brusseau, 2018).
The environmental mobility of PFAS depends upon compound-specific physical and chemical properties, including carbon chain length, functional group chemistry, water solubility, sorption characteristics, and interactions with organic carbon and mineral surfaces. While some PFAS exhibit stronger adsorption to soils and sediments, others remain highly mobile in groundwater, allowing migration over substantial distances once introduced into the subsurface. This combination of atmospheric transport, environmental persistence, and groundwater mobility distinguishes PFAS from many other industrial contaminants and underscores the importance of evaluating the complete source-to-receptor pathway when conducting environmental forensic investigations involving air emissions and potential drinking water impacts (Interstate Technology & Regulatory Council [ITRC], 2024; National Academies of Sciences, Engineering, and Medicine, 2022).
Methods
A multidisciplinary environmental forensic investigation was conducted to evaluate the potential for airborne PFAS emissions from an industrial thermal treatment operation to contribute to regional environmental contamination through atmospheric transport, deposition, and subsequent migration into groundwater resources. The investigation integrated environmental chemistry, atmospheric science, hydrogeology, environmental engineering, exposure assessment, toxicology, and regulatory analysis to develop a scientifically supported evaluation of the complete source-to-receptor pathway. Rather than relying upon a single dataset, multiple independent lines of scientific evidence were evaluated collectively using a weight-of-evidence approach to reconstruct contaminant releases, characterize environmental transport mechanisms, and assess the plausibility of long-term environmental impacts (U.S. Environmental Protection Agency [EPA], 2024; Interstate Technology & Regulatory Council [ITRC], 2024).
The investigation began with a comprehensive review of publicly available regulatory information, emissions inventories, environmental reporting records, engineering documentation, operational information, scientific literature, and environmental monitoring data relevant to PFAS emissions and transport. Reported emissions data were evaluated to characterize the quantities of PFAS and PFAS precursor compounds associated with historical industrial operations. Particular attention was given to understanding the methodologies used to estimate reported emissions, evaluating the assumptions incorporated into those calculations, and assessing how variations in operational performance could influence actual environmental releases. This evaluation provided the foundation for subsequent environmental fate and transport analyses (U.S. EPA, 2024).
Engineering analyses were performed to evaluate thermal treatment processes and the factors influencing PFAS destruction efficiency. Because complete thermal destruction of fluorinated compounds depends upon maintaining appropriate operating temperatures, residence times, mixing conditions, and combustion efficiency, the investigation reviewed published scientific literature describing PFAS destruction during thermal treatment and the potential formation or release of incompletely destroyed fluorinated compounds under non-ideal operating conditions. Operational performance information and regulatory compliance records were evaluated within the context of current scientific understanding regarding PFAS thermal destruction to assess the potential influence of process variability on atmospheric emissions (Aleksandrov et al., 2019; Shields et al., 2023).
Atmospheric transport was evaluated using AERMOD, the U.S. Environmental Protection Agency’s preferred regulatory air dispersion model for near-field applications. Representative emission rates, meteorological observations, terrain characteristics, and particle properties were incorporated into the modeling to estimate atmospheric transport and surface deposition of airborne PFAS under representative operating conditions. Multiple modeling scenarios were evaluated to assess the sensitivity of predicted deposition patterns to particle behavior and transport assumptions. The resulting deposition estimates were compared with available environmental information and current scientific understanding of PFAS atmospheric transport to evaluate the consistency of modeled contaminant migration with observed environmental conditions (U.S. EPA, 2024; American Meteorological Society & U.S. EPA, 2019).
To evaluate long-term environmental impacts, atmospheric deposition estimates were integrated with established principles of contaminant fate and transport. The investigation considered the movement of PFAS following deposition onto soils, vegetation, and surface waters, including infiltration through the vadose zone, migration within groundwater systems, partitioning between environmental media, and persistence within the subsurface environment. Published hydrogeologic and environmental chemistry literature describing PFAS mobility, sorption behavior, and groundwater transport was incorporated into the evaluation to determine whether atmospheric deposition could contribute to long-term groundwater contamination through natural environmental processes (Brusseau, 2018; Cousins et al., 2020).
Finally, all available information—including emissions data, engineering evaluations, atmospheric dispersion modeling, hydrogeologic analyses, environmental monitoring information, regulatory documentation, and peer-reviewed scientific literature—was synthesized using a weight-of-evidence framework. This multidisciplinary approach allowed independent scientific disciplines to corroborate one another, providing a comprehensive environmental forensic assessment of PFAS emissions, atmospheric transport, environmental persistence, groundwater migration, and potential human exposure. By integrating multiple complementary analytical methods, the investigation developed a scientifically rigorous evaluation of complex environmental processes affecting persistent fluorinated contaminants while demonstrating the importance of multidisciplinary environmental forensics in emerging contaminant investigations (National Academies of Sciences, Engineering, and Medicine, 2022; U.S. EPA, 2024).
Results
The environmental forensic investigation demonstrated that multiple independent lines of scientific evidence support a plausible source-to-receptor pathway linking airborne PFAS emissions from an industrial thermal treatment operation to environmental deposition and subsequent migration through the surrounding environment. Evaluation of emissions inventories, engineering information, atmospheric dispersion modeling, published scientific literature, and regulatory documentation consistently indicated that airborne PFAS released during industrial operations can be transported beyond facility boundaries, deposited onto terrestrial and aquatic environments, and ultimately contribute to long-term environmental loading. Rather than relying upon any single analytical technique, the investigation integrated complementary datasets that independently supported the overall conceptual site model of atmospheric transport, deposition, and environmental migration (U.S. Environmental Protection Agency [EPA], 2024; Interstate Technology & Regulatory Council [ITRC], 2024).
Atmospheric dispersion modeling demonstrated that airborne PFAS emissions are capable of traveling substantial distances before deposition, with predicted deposition patterns controlled by emission characteristics, particle properties, local meteorology, terrain, and atmospheric stability. The modeling illustrated that contaminant deposition is not confined to areas immediately surrounding an emission source but may occur across broad portions of the surrounding landscape, particularly during long-term routine operations. These modeled deposition patterns were consistent with the current scientific understanding of atmospheric transport for particle-associated PFAS and with recent peer-reviewed research demonstrating that fine PFAS-containing aerosols can undergo regional and, under some conditions, long-range atmospheric transport before deposition (Sha et al., 2025; American Meteorological Society & U.S. EPA, 2019).
Evaluation of reported emissions information indicated that assumptions regarding destruction efficiency can substantially influence estimated atmospheric releases of PFAS. Because relatively small changes in destruction efficiency may result in large differences in calculated emissions when processing substantial quantities of PFAS-containing materials, sensitivity analyses demonstrated the importance of carefully evaluating engineering assumptions incorporated into emissions estimates. The investigation found that emission estimates should be interpreted within the context of actual operating conditions, process variability, and current scientific understanding of PFAS thermal destruction rather than relying exclusively on theoretical performance assumptions (Shields et al., 2023; U.S. EPA, 2024).
Following atmospheric deposition, the investigation identified scientifically supported mechanisms through which PFAS may infiltrate soils, migrate through the vadose zone, and ultimately reach groundwater resources. Current hydrogeologic research demonstrates that many PFAS compounds exhibit substantial environmental persistence and mobility, allowing deposited contaminants to remain available for long-term transport following release. Depending upon local hydrogeologic conditions, infiltration rates, soil characteristics, and groundwater recharge, atmospheric deposition may represent a continuing source of PFAS loading to underlying groundwater systems over extended periods. This integrated understanding of atmospheric deposition and subsurface transport supports the importance of evaluating environmental media collectively rather than independently when investigating persistent contaminants (Brusseau, 2018; Cousins et al., 2020).
The investigation also demonstrated the importance of integrating environmental forensic disciplines when evaluating emerging contaminants such as PFAS. Atmospheric dispersion modeling alone cannot fully characterize long-term environmental impacts without considering environmental persistence, groundwater transport, engineering performance, regulatory information, and current toxicological knowledge. Likewise, groundwater monitoring data alone cannot fully explain contaminant origin without evaluating historical emissions and atmospheric transport pathways. By integrating engineering analyses, atmospheric science, environmental chemistry, hydrogeology, exposure assessment, and peer-reviewed scientific literature using a weight-of-evidence framework, the investigation developed a comprehensive scientific evaluation of contaminant fate and transport that extended beyond traditional single-media environmental assessments. This multidisciplinary approach provided a robust environmental forensic framework for evaluating potential PFAS migration from industrial air emissions through multiple interconnected environmental pathways (National Academies of Sciences, Engineering, and Medicine, 2022; U.S. Environmental Protection Agency [EPA], 2024).
Conclusions
This environmental forensic investigation demonstrated the importance of evaluating PFAS contamination using a comprehensive, multimedia approach that integrates atmospheric science, environmental chemistry, hydrogeology, engineering, toxicology, exposure assessment, and environmental modeling. Unlike many conventional contaminants that are evaluated within a single environmental medium, PFAS require consideration of interconnected transport processes linking air emissions, atmospheric deposition, soil contamination, groundwater migration, surface water interactions, and potential drinking water exposures. By integrating multiple independent scientific disciplines, the investigation developed a scientifically supported conceptual model describing how airborne PFAS emissions may contribute to long-term environmental contamination through well-established fate and transport mechanisms (U.S. Environmental Protection Agency [EPA], 2024; Interstate Technology & Regulatory Council [ITRC], 2024).
The investigation demonstrated that atmospheric emissions should be considered an important component of PFAS source characterization and environmental risk assessment. Air dispersion modeling, engineering analyses, emissions evaluations, and peer-reviewed scientific literature collectively demonstrated that airborne PFAS can be transported beyond facility boundaries, deposited onto terrestrial and aquatic environments, and subsequently migrate into groundwater through natural hydrologic processes. These findings reinforce the importance of evaluating complete source-to-receptor pathways rather than focusing exclusively on groundwater or surface water investigations after contamination has already occurred (Sha et al., 2025; Brusseau, 2018).
The investigation further illustrated that assumptions regarding emission estimates and destruction efficiencies can substantially influence predicted environmental releases and resulting exposure assessments. Accordingly, environmental forensic evaluations should consider not only reported emissions but also the engineering and operational factors that influence contaminant generation, treatment performance, and long-term environmental loading. Integrating engineering evaluations with atmospheric dispersion modeling and environmental fate and transport analyses provides a more scientifically robust understanding of PFAS migration than any single analytical method alone and improves confidence in source attribution and exposure reconstruction (Shields et al., 2023; U.S. Environmental Protection Agency [EPA], 2024).
This case study highlights the expanding role of environmental forensics in addressing emerging contaminants whose behavior spans multiple environmental media and extends over long periods of time. By combining advanced air dispersion modeling, environmental chemistry, hydrogeologic evaluation, contaminant fate and transport analysis, exposure science, and toxicological interpretation, RoseyFields provides scientifically rigorous assessments capable of evaluating complex environmental contamination scenarios involving persistent fluorinated compounds. These multidisciplinary investigations support environmental consulting, regulatory investigations, environmental due diligence, and expert witness services by providing objective, evidence-based evaluations of contaminant migration, source attribution, and potential human exposure using accepted scientific methodologies and current environmental science.
This investigation was conducted under the direction of Dr. Paul Rosenfeld, an environmental scientist and environmental forensic expert with extensive experience in PFAS investigations, air emissions analysis, atmospheric deposition modeling, groundwater contamination assessment, source attribution, and human health exposure evaluation. Dr. Rosenfeld’s work focuses on complex environmental contamination matters involving per- and polyfluoroalkyl substances (PFAS), emerging contaminants, industrial air emissions, environmental fate and transport, subsurface migration, drinking water impacts, and long-term multimedia exposure pathways affecting residential, commercial, municipal, and industrial settings. His expertise includes evaluating complete source-to-receptor pathways through the integration of air dispersion modeling, hydrogeologic analysis, environmental chemistry, contaminant transport, exposure assessment, toxicology, and regulatory science to determine whether airborne emissions may contribute to soil, groundwater, surface water, and drinking water contamination. Through RoseyFields LLC, Dr. Rosenfeld provides environmental forensic analysis, environmental due diligence, regulatory and compliance support, toxic tort and personal injury case evaluation, and expert witness testimony involving PFAS contamination, industrial releases, atmospheric transport, groundwater migration, and long-term environmental and human health risks.
References
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Brusseau, M. L. (2018). Assessing the potential contributions of additional retention processes to PFAS retardation in the subsurface. Science of the Total Environment, 613–614, 176–185.
Cousins, I. T., DeWitt, J. C., Glüge, J., Goldenman, G., Herzke, D., Lohmann, R., Ng, C. A., Scheringer, M., & Wang, Z. (2020). Strategies for grouping per- and polyfluoroalkyl substances (PFAS) to protect human and environmental health. Environmental Science: Processes & Impacts, 22(7), 1444–1460.
Interstate Technology & Regulatory Council. (2024). PFAS: Per- and polyfluoroalkyl substances guidance document. Interstate Technology & Regulatory Council.
National Academies of Sciences, Engineering, and Medicine. (2022). Guidance on PFAS exposure, testing, and clinical follow-up. National Academies Press.
Sha, B., Dalmijn, J., Johansson, J. H., Salter, M. E., & Cousins, I. T. (2025). Emission of perfluoroalkyl acids and perfluoroalkyl ether carboxylic acids to the atmosphere from a fluorochemical industrial park in China. Environmental Science & Technology, 59(11), 6719–6728.
Shields, E. P., Krug, J. D., Roberson, W. R., et al. (2023). Pilot-scale thermal destruction of per- and polyfluoroalkyl substances in a legacy aqueous film-forming foam. ACS ES&T Engineering, 3(9), 1308–1317.
U.S. Environmental Protection Agency. (2024). Interim guidance on the destruction and disposal of perfluoroalkyl and polyfluoroalkyl substances and materials containing perfluoroalkyl and polyfluoroalkyl substances (Version 2). U.S. Environmental Protection Agency.
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